The overall objectives of this program are to obtain in vitro measurements of the wall shear stress, wall pressure, and detailed intralumenal flow patterns produced by pulsatile flow through models of arterial bifurcations. Both the pulsatile flow waveforms and the model geometries conform to conditions existing in the adult human aorto-iliac and carotid bifurcations. Measurements are made with hot-film wall probes and special pressure transducers, and consist of low-frequency data (including low harmonics of the cycle pulsatile frequency) as well as time-resolved power spectral densities of the higher harmonic components characteristic of disturbed and turbulent flow. A laser-induced fluorescence technique will be used to obtain spatially- and temporally-resolved flow patterns and velocities. The measured flow conditions will be related to possible changes in structure and function of arterial endothelium.